Document Type : Original article
Subjects
Abstract
Background: The aim of this study was to investigate the relationship between blood groups and personality types, and medication adherence in Type 2 Diabetes Mellitus (T2DM).
Methods: 302 patients with T2DM were considered in the study. Their sociodemographic information and medical history were recorded. Type D personality and medical adherence were checked using DS-14 and MMAS-8 questionnaires, respectively. Blood samples were obtained from the patients to determine the types of ABO blood groups, HbA1c, fasting blood sugar and lipid profile.
Results: No significant association was found between the patients’ characteristics including demographic and laboratory information and medical adherence to treatment. However, a significant difference in medical adherence was observed between patients with type D personality. According to logistic regression model, patients with type D [OR: 6.23, (95%CI: 2.34-16.55, p<0.001] had better adherence to medication, while the blood groups was not associated with medical adherence to treatment.
Conclusion: Type D personality cannot impair medical adherence in these patients. There was an association between type D personality and the ABO blood group, but the ABO blood group was not related to medical adherence.
Keywords: ABO blood-group system, Blood glucose, Diabetes mellitus Type 2, Glycated hemoglobin, Logistic models, Medication adherence, Type D personality
Introduction
Diabetes Mellitus (DM) refers to a group of metabolic disorders (1) that eventually cause an elevated risk of morbidity and mortality. The prevalence of adults with DM was 8.8% in 2015, and is predicted to increase to 10.4% by 2040 (2). Moreover, based on the assessments done in 2013 by the International Diabetes Federation (IDF), there are 382 million adults with Type 2 DM (T2DM) worldwide, 80% of which are from low- and middle-income countries (3,4). In fact, Iran was declared to be the second country in the Middle East in 2017 to have the highest number of patients diagnosed with T2DM (5).
Like other complex chronic diseases, T2DM needs constant treatment, thus necessitating extended lifelong care and consideration by healthcare personnel and patients (6). Accordingly, the main goal is to control glycemic indexes and reduce the complications of T2DM. Almost less than half the patients with T2DM encounter poor glycemic maintenance (HbA1c <7%) (7), which is mainly attributed to non-adherence or non-compliance to medication, indigence, lack of awareness, and inadequate follow-ups (8).
Medication adherence has been previously reported to be extensively varied in the patients with DM (9). An increased rate of medical complications such as cardiovascular diseases and mortality, as well as reduced quality of life, are the important consequences of poor medication adherence in these patients. Therefore, in order to maintain their health and prevent these complications, adherence to medication and treatment compliance is required (10). In this regard, one factor complicating the implementation of self-management could be different personality types; for example, type D personality, characterized by less frequent consultation with the doctor, makes both the physician and the person with this personality type unaware of the increased risk induced by diseases (7). Type D personality describes individuals who experience high levels of Negative Affectivity (NA) and Social Inhibition (SI) (11).
A significant association between type D personality and an increased risk of negative medical outcomes and poor medication adherence in the individuals suffering from chronic diseases and cardiovascular diseases has been previously reported (12). Previous study has been suggested that the type D personality could not impair the medication adherence of diabetic patients, but no consensus has been reached yet (13).
A recent study has been suggested an association between personality traits and ABO blood groups (14). For instance, AB blood group is more related to introvert behaviors, compared with the other blood groups (15). Moreover, the relationship between DM and ABO blood types has been studied previously (16). However, to the best of our knowledge, the relationship between blood groups and medication adherence with regard to personality types has not been investigated before.
Materials and Methods
Participants
This was a cross-sectional observational study conducted from 2016 to 2017. This research has been performed in accordance with the Declaration of Helsinki and has been approved by the Ethics Committee of by the Islamic Azad University. 302 patients, diagnosed with T2DM by an endocrinologist, according to the World Health Organization (WHO) criteria (17), were recruited from individuals referring to Shaban-Ali Clinic in Isfahan, Iran. Patients suffered from T2DM at least one year and at most, 35 years, with an age range of 23-89 years. The aim of the study was explained to the participants and written informed consent was obtained. Written informed consent was obtained from the patients (or their parent or legally authorized representative in the case of children under 18 years of age).
Demographic information
Patients’ demographic information, namely, age, sex, level of education, marital status, Body Mass Index (BMI) (kg/m2) (low: <20, middle: 20-24.9, high: 25-29.9, fat:>30) (18), and their medical history [such as HbA1c (%), duration (year), and complications of T2DM, including hypertension, neuropathy and cardiovascular disease and family history of T2DM], were recorded. Blood samples were obtained from the patients to determine the types of ABO blood groups (A, B, AB, and O). HbA1c served as the marker of the average glycemic control, fast blood sugar (FBS, mg/dl) and lipid profile (mg/dl). Lipid profiles, FBS and HbA1c were measured by Pars Azmoon kit (Iran), using a photometric method, and blood groups were determined using the Sinnagen kit (Iran).
Type D personality
In order to establish type D personality, the Persian version of the Type D personality scale (DS-14) questionnaire, developed by Denolet (19,20), was used. The questionnaire contains 14 items divided into two groups of 7, each for NA and Social Inhibition (SI). The NA comprises dysphoria, worry and irritability, and SI consists of discomfort in social interactions, reticence and social self-control. Scores were calculated based on a five-point Likert scale ranging from zero (false) to four (true), ranging from zero to 56. Also, in some studies, a cut-off equal or higher than ten in both subscales (NA and SI) was considered as type D personalities (19,20), but DS-14 score concordance was categorized with another paper by its original quartiles; lower than 15, 15 to 28, 29 to 42 and greater than 42 (21), It should be noted that the original median (score ≥29) was used in the logistic regression model. Cronbach’s α for NA and SI subscales was 0.84 and 0.86, respectively, in the Persian Version of DS-14 (19). In this study, Cronbach’s α was 0.88 and 0.86 for NA and SI, respectively. Afterwards, the Persian version of the 8-item Morisky medication adherence scale (MMAS-8) questionnaire, was given to the patients as a validated measurement tool used for non-adherence to medication (22,23). The questionnaire consisted of seven two-choice questions, where 1 means Yes and 0 stands for No; it includes five-point questions whose scores are based on five-choices: “never=0, rarely= 1, sometimes=2, often=3 and always=4”. A score of 6 or higher is considered to be optimal adherence to medication (22).
Statistical analysis
The descriptive statistics was presented as mean±Standard Deviation (SD) and frequency as deemed normal distribution. Also, we used Chi-square or Fisher’s exact, t, and one-way ANOVA. In addition, multiple logistic regression models were employed to calculate the Odds Ratio (OR) as an estimate of the relative risk of the different variables for the type D personality and medical adherence in model 1. Furthermore, the significant variables in model 1 and ABO blood groups is fitted in model 2. Statistical analysis was performed using Statistical Package for the Social Sciences software (SPSS, Version 23) by considering significant level less than 0.05.
Results
In this study, 302 patients with T2DM, including 156 men and 146 women, were recruited. The medical adherence to treatment among people with T2DM was 11.6%. The medical adherence status of the patients with regard to their socio-demographic, clinical and laboratory information is shown in table1.
Table 1. The univariate relationship between patients’ characteristics between medical and non-medical adherence
|
|
Medical adherence N=35 |
Non-medical adherence N=267 |
p-value |
|
|
Gender |
Male |
18(11.5) |
138(88.5) |
0.962 |
|
Female |
17(11.7) |
129(88.3) |
||
|
Age (years) |
≤45 |
2(8.7) |
21(91.3) |
0.653a |
|
>45 |
33(11.8) |
246(88.2) |
||
|
Marital status |
Married |
33(11.4) |
257(88.6) |
0.641a |
|
Single and Divorced |
2(16.6) |
10(83.4) |
||
|
Education level |
College education |
3(8.6) |
32(91.4) |
0.583a |
|
Diploma and under |
22(8.2) |
245(91.8) |
||
|
Occupation |
Retired |
9(11) |
73(89) |
0.878 |
|
Housewife |
15(11) |
121(89) |
||
|
Occupied |
11(13.1) |
73(86.9) |
||
|
Family history |
Positive |
27(12.4) |
190(87.6) |
0.390 |
|
Negative |
7(8.9) |
72(91.1) |
||
|
BMI kg/m2 |
<25 |
11(11.2) |
87(88.8) |
0.894 |
|
≥25 |
24(11.8) |
180(88.2) |
||
|
|
|
Mean±SD |
|
|
|
HbA1C (%) |
|
7.82±1.65 |
7.59±1.44 |
0.472 |
|
FBS mg/dl |
|
152.34±51.97 |
152.51±55.26 |
0.662 |
|
TG mg/dl |
|
164.57±70.63 |
147.55±77.52 |
0.100 |
|
Cholesterol mg/dl |
|
154.77±37.45 |
149.22±34.00 |
0.263 |
|
HDL mg/dl |
|
41.46±10.80 |
43.06±8.49 |
0.449 |
|
LDL mg/dl |
|
82.09±27.09 |
81.04±21.86 |
0.660 |
a: Fisher-exact test
FBS=Fasting Blood Sugar, TG=Triglycerides, HDL=High-Density Lipoprotein, LDL=Low-Density Lipoprotein, BMI=Body Mass Index.
Overall, no significant association was found between the patients’ characteristics including demographic, laboratory information, and their adherence to treatment. The mean score of type D personality (p<0.001), social inhabitation (p<0.001), and negative affectivity (p=0.001) were statistically higher in patients with medical adherence rather than those without medical adherence (Table 2).
able2. Comparison of type D personality score between medical and non-medical adherence among patients with T2DM
|
|
Non-medical adherence |
Medical adherence |
p-value |
|
|
Mean±SD |
||||
|
Social inhabitation |
12.5±4.7 |
15.7±3.8 |
<0.001 |
|
|
|
14.4±6.7 |
18.5±5.8 |
0.001 |
|
|
“Negative affectivity” |
|
26.9±9.8 |
34.3±8.2 |
<0.001 |
|
|
N (%) |
|
||
|
<=14 |
28(100) |
_ |
0.002 |
|
|
15-28 |
124(93.2) |
9(6.8) |
||
|
29-42 |
99(83.2) |
20(16.8) |
||
|
>42 |
16(72.7) |
6(27.3) |
||
There was positive relationship between type D personality and medical adherence to treatment.
When the four ABO blood groups were considered, as shown in table 3, medical adherence did not generally show any significant differences, based on type D personality in the patients with T2DM in different blood groups.
Table 3. Comparison of medical adherence in patients with type 2 diabetes mellitus in different ABO blood groups (A,B,AB, or O) in totally and type D personality
|
|
|
A |
B |
O |
AB |
p-value |
|
Total |
Non-medical adherence (%) |
16.7% |
10.7% |
7.5% |
11.1% |
0.240a |
|
Medical adherence (%) |
83.3% |
89.3% |
92.5% |
88.9% |
||
|
Type D personality score |
Non-medical adherence |
28.2±9.9 |
28.1±10.3 |
25.6±9.5 |
23.9±8.4 |
0.093b |
|
Medical adherence |
32.8±7.9 |
38.4±6.4 |
33±11.3 |
35.3±3.1 |
0.435b |
a: chi-suare test, b: one-way ANOVA test.
Then, logistic regression models were performed to predict Type D personality. As shown in table 4, in model 1 by considering the socio-demographic and clinical variables there was no statistically significant variables related to type D personality except that the relative risk of type D in women is one times higher than men. In model 2 by regarding sex and ABO blood groups, sex had a positive relationship (p=0.013) with type D personality; It means that women were (OR: 2.01, 95%CI:1.29, 3.37) more likely to have type D personality when compared to men, as well as blood group B had a higher chance of predicting type D personality (OR: 3.59, 95%CI: 1.39, 9.24, p=0.008, Table 4).
Table 4. Logistic regression models to predicting type D personality according to patients’ variables
|
Model 1a |
Model 2b |
|||||
|
Variables |
OR(95%CI) |
p-value |
Variables |
OR(95%CI) |
p-value |
|
|
Age ≤45 vs. >45 yrs |
0.80(0.28,2.27) |
0.681 |
Female vs. Male |
2.01(1.29,3.37) |
0.003 |
|
|
Female vs. Male |
2.01(1.22,3.56) |
0.007 |
Blood group A vs. AB |
2.20(0.88,5.53) |
0.090 |
|
|
Married vs. Single |
1.12(0.25,4.96) |
0.873 |
Blood group B vs. AB |
3.59(1.39,9.24) |
0.009 |
|
|
College education vs. diploma and under diploma |
1.86(0.66,5.27) |
0.243 |
Blood group O vs. AB |
1.58(0.63,3.95) |
0.325 |
|
|
BMI <25 vs. ≥25 (kg/m2) |
0.73(0.43,1.24) |
0.254 |
|
|
|
|
|
HbA1C (%) |
1.01(0.81,1.26) |
0.910 |
|
|
|
|
|
Duration (year) |
1.01(0.98,1.04) |
0.562 |
|
|
|
|
|
Family history |
1.11(0.94,1.93) |
0.700 |
|
|
|
|
|
Blood pressure (mmHg) |
1.06(0.60-1.85) |
0.957 |
|
|
|
|
|
FBS (mg/dl) |
1(0.99-1.00) |
0.900 |
|
|
|
|
|
TG (mg/dl) |
1.00(0.99-1.00) |
0.756 |
|
|
|
|
|
HDL (mg/dl) |
0.99(0.96-1.02) |
0.644 |
|
|
|
|
|
Cholesterol (mg/dl) |
0.99(0.97-1.01) |
0.258 |
|
|
|
|
|
LDL (mg/dl) |
1.01(0.99,1.04) |
0.272 |
|
|
|
|
a: model adjusted by demographics and clinical variables, b: significant variables in model 1 and ABO blood group.
FBS=Fasting Blood Sugar, TG=Triglycerides, HDL=High-Density Lipoprotein, LDL=Low-Density Lipoprotein.
As shown in table 5, logistic regression models were conducted to predict medication adherence. Cholesterol was statistically related to medical adherence (p=0.048). Also, there was a positive relationship between type D personality and medical adherence. Indeed, patients with type D personality OR: 6.23, (95%CI: 2.34-16.55, p<0.001) had better adherence to medication by controlling socio-demographics and clinical covariates (model 1). Furthermore, there was no relationship between the ABO blood group’s medication adherence when the type D was simultaneously in model by adjusting sex and age (model 2, Table 5).
Table 5. Logistic regression models to predicting medical adherence
|
Model 1a |
Model 2b |
||||
|
Variables |
OR(95%CI) |
p-value |
Variables |
OR(95%CI) |
p-value |
|
Age (year) |
1.71(0.25,11.46) |
0.579 |
Age (year) |
1.46(0.31,6.82) |
0.633 |
|
Sex female vs. male |
0.78(0.32,1.86) |
0.570 |
Sex Female vs male |
0.79(0.37,1.69) |
0.543 |
|
Married vs. single |
3.14(0.37,26.8) |
0.293 |
Type D personality |
3.93(1.72,9.02) |
0.001 |
|
College education vs. diploma and under diploma |
1.95(0.21,18.20) |
0.556 |
Blood group A vs. AB |
1.32(0.33,5.21) |
0.759 |
|
Normal BMI vs. abnormal (kg/m2) |
0.79(0.32,1.95) |
0.600 |
Blood group B vs. AB |
0.67(0.15-2.90) |
0.333 |
|
HbA1C(%) |
1.03(0.75,1.43) |
0.855 |
Blood group O vs. AB |
0.59(0.14,2.53) |
0.48 |
|
Duration(year) |
1.01(0.96,1.07) |
0.670 |
- |
- |
- |
|
Family history |
1.71(0.62,4.70) |
0.300 |
- |
- |
- |
|
Blood pressure(mmHg) |
1.35(0.58,3.11) |
0.493 |
- |
- |
- |
|
FBS(mg/dl) |
0.99(0.99,1.01) |
0.833 |
- |
- |
- |
|
TG(mg/dl) |
1.00(0.99,1.01) |
0.833 |
- |
- |
- |
|
HDL(mg/dl) |
0.97(0.92,1.02) |
0.262 |
- |
- |
- |
|
Cholesterol(mg/dl) |
1.02(1.001,1.04) |
0.043 |
- |
- |
- |
|
LDL(mg/dl) |
0.98(0.95,1.01) |
0.151 |
- |
- |
- |
|
Type D personality |
6.23(2.34-16.55) |
<0.001 |
- |
- |
- |
a: adjusted model by demographics and clinical variables, b:significant variables in model 1 and ABO blood group also, adjusted by sex and age.
FBS=Fasting Blood Sugar, TG=Triglycerides, HDL=High-Density Lipoprotein, LDL=Low-Density Lipoprotein.
Discussion
Medical adherence is an indispensable factor for metabolic maintenance and mitigation of complications (5). Based on the results of this study, medication adherence in type D personality and non-type D personality groups was significantly undesirable; however, compared to the other personality types, type D showed significantly better adherence to treatment. Similar result was extracted from another article (10).
A significant association between type D personality with the increased risk of negative medical outcomes and poor medication adherence in the individuals suffering from chronic diseases and cardiovascular diseases has also been reported (7,11). Type D personality was introduced as a comparably novel risk factor requiring particular clinical attention in patients with DM since association was mostly demonstrated with poor prognosis (24).
There have been many studies on the association between type D personality and medical adherence in various diseases. In most of such studies, individuals with type D personality have shown less interest in consultation with their physician (25), and poor medication adherence, especially for metabolic syndromes; this could increase the risk of developing these diseases (26-30).
In addition, in a similar study performed in 2016 in a T2DM Chinese population, type D personality was shown to be associated with medication adherence (31). In addition, in one other study, individuals with asthma were examined with respect to their personality traits and reports of asthma symptoms. It was shown that people who experienced high levels of NA sometimes behaved correctly, because they were worried about their illness and showed interest in being aware of the symptom-related disease. This study revealed that patients with high levels of NA were associated with increased reports of symptoms (32). However, in a comparable study done in the Netherlands in 2015, the researchers showed that although type D personality was related to negative emotions and unhealthy behaviours, it was not associated with any standard biomedical risk factors (33).
Moreover, medical adherence in patients with DM with different ABO blood groups was evaluated and compared in the patients with type D personalities. In this comparison, medication adherence was more desirable individuals with type D personality and AB blood group. In patients with DM with type D and blood groups A, B and O, with/without considering the personality type, individuals with blood group A had a relatively better medication adherence while the O blood type was the most undesirable.
There is, however, no previous study evaluating the relationship between medication adherence and blood groups; so, for the first time, this study measured this relationship directly in a T2DM population in Iran. In the recent years, several studies have examined the relations between blood groups and behavioral patterns. For instance, in a study conducted in India in 2018, a significant association was seen between the AB blood group and extraversion behavioral patterns (34). Previous studies have also reported that medication adherence varies widely, depending on many factors such as age (35), education level, and socioeconomic status (36). However, in the present study, no significant differences were observed with respect to the obtained results and comparison of adherence to medication in each demographic factor. First, it was found that sex had no significant impact on medical adherence to the disease. Based on previous studies, few differences could be found in the suggestions made by health experts. Regarding the aspects of self-care, the gender difference was also negligible (37). although many similar studies have indicated that women have a stronger medical adherence than men (38). Analysis of this study showed that women had more type D presentation when compared with men and sex had a positive relationship with type D personality. It means that women have a higher chance of developing type D personality when compared to men. The results of a study done in Poland also showed the higher values of NA and SI in women, not men. There were sex differences in type D personality as well (39). Analysis of the current study showed that type D personality had a positive relationship with medication adherence. In addition, some studies show that type D personality was associated with medical adherence in patients with cardiac disease. (40,41) NA component of the type D personality is associated with medical adherence through self-efficacy (7,42,43), and SI is related to medication adherence too (25). According to the social cognitive theory by Bandura, self-efficacy is an important mediator between type D personality and medical adherence (44). A study conducted on patients with Acute Coronary Syndrome (ACS) showed that NA and SI had a significant relationship with medication adherence (7). A previous study also showed an association between type D personality and medication adherence in the patients with heart failure (42), when type D personality was analyzed as a categorical variable. Contrary to the mentioned studies, two studies indicated that the type D personality was not associated with medication adherence in the patients with ACS (7), HF (42). The results of the present study also indicated no significant association between age groups and medication adherence. Previous studies examining the association between age and medication adherence in the patients with chronic heart failure found significant age-related medication adherence (42).
The results of this study showed that married people were more committed to their treatment. It was also shown that single patients with heart failure were less likely to adhere to their treatment and experience more cardiovascular events (45). However, the results of the present study showed that education level, occupation and relative social status were not related to their medication adherence. In the present study, more than 70% of the patients had a positive family history, but this did not lead to a significant relationship with medication adherence. Most of the subjects in this study were classified as having a high BMI. Sacco and colleagues showed that a high BMI could lead to depression in adults with DM (46). Moreover, no association to HbA1c was found. Analogous to the present study results, in a study done in Nigeria in 2015, demographic data showed that only sex had a significant relationship with medication adherence, and no significant association was found among other factors (47).
Conclusion
In this study, a significant difference in medical adherence was observed between patients with type D personality; while the blood groups were not associated with medical adherence to treatment.
However, given the overall poor medical adherence in patients with DM, more attention should be paid to the follow-up treatment and regular contact with the physician. The impact of this cultural defect could cause type D personality features not only to be absent, but also to have more positive results in this field and cultural context.
Ethical issue
All procedures were approved by the Islamic Azad University, Najafabad branch, Research Ethics Committee and were in accordance with the Declaration of Helsinki and APA ethical standards. The aims of the study were explained to the participants and the written informed consent was obtained.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Limitations
We are aware of the limitations of our study. First, the number of final participants was low. Although we obtained meaningful data, the result was not as much satisfactory as we wished. Moreover, our patients were all from one city. In other words, sample selection was limited to one part of the country, so cultural bias might have affected the results. Therefore, we suggest continuing the research in the form of a prospective study, along with strategies to encourage the participation of more patients from different parts of Iran.
Acknowledgement
The authors would like to thank all who collaborated in this study.
Conflict of Interest
There was no conflict of interest in this manuscript.
